1. Field of the Invention
This invention relates to a method and recording apparatus for detecting a rear edge of a recording medium with a recording apparatus.
2. Description of Related Art
Conventionally, as a means to detect a sheet being a recording medium, a recording apparatus such as a serial type ink jet printer or the like was provided with a swinging type passage detection lever for swinging depending on a presence of a sheet, and a detection sensor of an optic type or the like for detecting a movement of the passage detection lever, wherein the passage detection lever and the detection sensor are arranged upstream at a prescribed distance apart from a recording head on a sheet conveying path. At a point of time when the detection sensor detects the movement of the passage detection lever, a control means manages a position of the sheet, and omits a portion of a printing data exceeding a length of a remaining area between a recording position of the recording head to a rear edge of the sheet based on the length of the remaining area, and proceeds printing. However, a mechanically driven type sheet detection means as the above causes a delay of sheet detection associating with the swinging of the passage detection lever. Although the delay time of the sheet detection is the same, a conveyed quantity during this time of delay would differ depending on a sheet conveying speed; accordingly, a method of determining the position of the rear edge of a sheet based on a maximum value of a sheet conveying speed or a method of detecting the position of the rear edge of a sheet according to a sheet conveying speed (Japanese Publication Hei10-058801) have been used.
Nevertheless, in respect of the conventional recording apparatus, a sheet conveying quantity differed depending on a printing content, and further, in a case where the sheet conveying quantity is small or in a case where a passage detection lever had been activated right before a cease of conveying, the detection sensor proceeds detection from a position where the conveying had ceased. Subsequently, the detection of the length of a remaining area between a recording position of the recording head to a rear edge of the sheet would become indefinite and variable; therefore, in a case where position is not adjusted, a design error was accumulated and printing was performed by maximizing a margin space to prevent discharging upon a platen portion.
This invention is aimed to improve printing quality by reducing a margin space of a rear edge of a recording medium in a case where the recording medium conveyed in a conveying direction is shorter than a data for printing.
In means to solve the foregoing problems, this invention provides a method of detecting a rear edge of a recording medium comprising: a passage detection lever for swinging in association with a passage of the rear edge of the recording medium; and a detection sensor for detecting the swinging movement of the passage detection lever, wherein the method of detecting the rear edge of the recording medium comprises the steps of: detecting a conveying quantity of the recording medium at each prescribed period; recording a past data of the conveying quantity of the recording medium; evaluating a physical returning time starting from a point of time when the rear edge of the recording medium has passed the passage detection lever to a point of time when the detection sensor detects the passage detection lever; and detecting a position of the rear edge of the recording medium based on the recorded past data regarding the conveying quantity of the recording medium.
In means to solve the foregoing problems, this invention further provides a recording apparatus for recording upon a recording medium by a recording head, wherein the recording apparatus comprises a memorizing means for detecting a recording medium conveying quantity at each prescribed period and memorizing the recording medium conveying quantity as a past data; a passage detection lever swinging in association to a passage of a rear edge of a recording medium; a detection sensor for detecting the swinging movement of the passage detection lever; and a controlling means for determining a position of the rear edge of a recording medium by evaluating a physical returning time starting from a point of time when the rear edge of the recording medium has passed the passage detection lever to a point of time when the detection sensor detects the passage detection lever